We've heard of this melting problem while trying to use the AC if one uses a 15 amp adapter on the male end of the 30 amp power cord. The heat pump still uses the AC compressor IIRC.

Same as the air conditioner -- ya need more available amps. The appliance (AC in this case) will try to pull the higher amperage thru an inadequate outlet & adapter.

Chuck has found a 20 amp outlet can be used if you aren't trying to run any other high-demand appliances on house current (eg, no microwave, put fridge on propane, etc) -- but most people don't even have 20 amp outlets in their home.

A poor connection at the plug, or within the plug, can cause heat when a draw is applied to the circuit. If there is a big draw, the weakest part of that circuit, perhaps where cords are plugged together, can get very hot.

All electric devices contain smoke. They will quit working if you let the smoke out.

Guage is very important.
When I was a Snap-On dealer we sold a set of very good jumper cables made from heavy welding cable and heavy duty clamps. Some would pass on them because of their hefty, nearly $50.00 price tag, and get the $7.95 junk from some other place.

After all, "I'm not going to use them every day, I only want them for an emergency."

Well DH returned with a problem, the shore power plug of the AS melted into the plug of the surge protector using the heat pump presumably.

Previously on a different AS the shore power plug melted into the heavy duty RV extension using the AC at home.

Is this an issue of available current or poor connections or what? Thanks in advance.

Carol,
Could be both. Dirty (not shinny) contact cause resistance which will raise the power (current) draw. Low voltage will raise the power (current) draw.
Too small a wire will raise power draw. Too much use will fray the wires at the end of the wire, this will cause an incrase in power draw. I had this happen and cut off the end of the trailer cable and put on a new 30A plug.
Problem solved.
I have been told by a good AS tech that if you do not twist lock and screw the collar down this can cause the receptical and plug in the AS to fuse together. An expensive fix.

Replace the cable and use 30A extension cables and a 30A outlet. I know you were doing this for you AS but with two do you have two 30A outlets on seperate circuits?

The shore power line should be capable of running what ever is in the unit. More than likely there is a poor connection inside the shore power plug so you're not getting the full use of the heavy gage wire. Is the surge protector rated for 30a ?

We had a similar problem with Lucy's 30 amp OEM shore power cord earlier this year. In May, we were camped at Quartzsite, Arizona. The daytime temperatures were spiking near 110 degrees. Lucy's air conditioner was running pretty much steadily during the day. Lucy was plugged into a 50 amp outlet using a 30 to 50 pigtail. Lucy's electric service continued to work for a couple of days. As we were braking camp, I noticed that the male end of Lucy's power cord was very hot as was the female end of the 50amp/30amo adapter. They had melted together.

I unplugged from the campground power outlet. The male end of the adapter was not warm at all. I was able to separate the pigtail adapter using a sharp knife. I was able to continue Lucy's long western trip using the same semi-melted power cord without any further problems. When we returned home two months later, I did replace the male end of Lucy's shore power cord. I have also replaced the 50 to 30 adapter.

We have one dedicated 30 amp connection run separate and directly from the main electrical box to the exterior covered garage wall plug at home and we only plug in one AS at a time.

Our extension cord is heavy duty 30 amp cord, same thickness as the shore power cord it looks like to me. We bought it from the AS factory. We have two extensions Michelle. Brad has bought a plastic covered connector box(?) and plugs the AS cord and extension cord into that, at home, since the melting eposode. It seems the plastic in between the rubber plugs makes a better seal or does not allow the rubber ends to melt together.

Brian, Brad will try his Exacto blade to separate the cords. For the time being they are still together. I may also pm you and Michelle about replacing the plug. He wants to replace the entire cord rather than mess with replacement.

All this troubleshooting is invaluable to us. I am appreciating everyone's input.

I wonder if the current going to the makeshift campsite where he seasoned was suspect, yet the Surge Guard would have kicked the electric off, I would have thought, before it would melt. How do you check the connection inside the shore power plug, or does he already know this? I am just the mediator and running between the trailer (it's a beautiful day here in Michigan) and the computer...I know he's got guages or meters.

Okay, look at the electrical system in its totality for a moment. each circuit in the AS is protected by a circuit breaker-if any individual load begins to draw more than the circuit breaker's rating-it will trip. Now, looking at the coach as a whole-it should never exceed 30 amps, right? well, no. If each of the individual circuits in your AS are drawing say 10 amps each, then if you have four circuits, you actually are drawing 40 amps. Now, knowing that is possible, if your umbilical is plugged into a 30 amp breaker, either in your surge protector, or in the circuit from home or rv camp or wherever then that breaker should operate. Now, you didn't say any circuit breaker operated-meaning the current flow through this umbilical never exceeded 30 amps. So what gives? Okay there is a mechanical connection that has begun to fail. that connection is/are the spades of the plug/receptacle. Those spades have introduced a resistance into the circuit and the result (energy usage) of that resistance is heat.

Okay, what is causing the resistance? Well, the physical connecting action of the plug/receptacle is supposed to "clean" the spades when inserted. However, the female receptacle's spring action of its contacts can become weakened over time, not cleaning the male spade's surface area, causing resistance. If the female end is "loose" (no offense intended), then it, too introduces resistance. Once the joint begins to heat, it becomes a heat sink, causing more and more heat until something oxidizes (burns) causing more resistance, and hence more heat.

Cure? keep contacts (male spades) clean, lubricate the receptacle with dielectric compound, insert the male plug straight into the female receptacle with as little side-to-side motion as is possible. Once a male end is heated like the one you have-time to cut it off and wire up a new one. When purchasing a new plug or receptacle, look at the construction of the piece-check out the "robustness" of the copper contacts-compare less expensive ones to more expensive ones-size does matter, here. a larger surface area (within the specifications of the plug/receptacle design) is better. Twist locks are probably better because of the physical twisting action of the contact connection. Plugs with the handle at the back may be better because they allow for straight pull apart action (no side-to-side). Once again, lubricate with dielectric compound.

The shore power plug in the picture looks to be molded whi ch means it cannot be checked . It can be cut off and a replacement put on , any RV dealer has them. With a bad connection at the plug I would think there would be a voltage drop between the house and trailer.

My A/S came with a somewhat-melted plug. It "appeared" that there was a high current-draw event of some sort that caused this (probably a poor internal connection, but it too was a molded plug that could not be checked) ... I cut it off and replaced it the week I got it, making sure all wires had a good connection. No problems since.